1. Field
One or more embodiments relate to an etching apparatus and method for a semiconductor device. More particularly, the embodiments relate to an etching method for a semiconductor device, capable of improving a selectivity of a photoresist in an etching process of the semiconductor device such as a wafer.
2. Description of the Related Art
In general, a device dimension of a semiconductor device is gradually becoming smaller, and thus, a photoresist is gradually becoming thinner in order to pattern a micro-sized structure.
Accordingly, a process enabling a thin photoresist to have a high selectivity is required.
U.S. Unexamined Patent Publication No. 2002/0102500 discloses a technology of forming a fluorinated carbon protecting layer. According to the above Publication, a step of depositing a protecting layer on a photoresist is added before an etching process such that the fluorinated carbon protecting layer can be formed by using CxHy-based etching gas such as fluoromethyl (CH3F), octafluorocyclobutane (C4F8), etc.
In detail, a material layer such as silicon oxide (SiO2) is formed on a wafer, and the photoresist is coated and developed on the material layer. At this time, the material layer is etched through the etching process.
It is preferable if the photoresist has higher selectivity during the etching process. Here, the photoresist selectivity is obtained by dividing an etching rate of a target material by an etching rate of a non-target material.
In the conventional technology, instead of immediately etching the wafer introduced into an etching chamber, the operation adding the fluorinated carbon protecting layer on the photoresist is previously performed to protect the photoresist. Thus, the etching process is performed after protecting the top and sidewall of the photoresist.
However, since the fluorine is added, porosity of the fluorinated carbon protecting layer becomes greater thereby weakening the protection strength. In addition, the etch resistance of the fluorinated carbon protecting layer becomes reduced due to the etching effect of the fluorine, so the coupling strength between the fluorinated carbon protecting layer and the photoresist becomes relatively weaker.
Accordingly, there is limitation in enhancing the selectivity of the thin photoresist, so the etching efficiency is degraded.